.\"	$OpenBSD: RAND_bytes.3,v 1.6 2018/03/27 17:35:50 schwarze Exp $
.\"	OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
.\"
.\" This file was written by Ulf Moeller <ulf@openssl.org>.
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.Dd $Mdocdate: March 27 2018 $
.Dt RAND_BYTES 3
.Os
.Sh NAME
.Nm RAND_bytes ,
.Nm RAND_pseudo_bytes
.Nd generate random data
.Sh SYNOPSIS
.In openssl/rand.h
.Ft int
.Fo RAND_bytes
.Fa "unsigned char *buf"
.Fa "int num"
.Fc
.Ft int
.Fo RAND_pseudo_bytes
.Fa "unsigned char *buf"
.Fa "int num"
.Fc
.Sh DESCRIPTION
These functions are deprecated and only retained for compatibility
with legacy application programs.
Use
.Xr arc4random_buf 3
instead.
.Pp
.Fn RAND_bytes
puts
.Fa num
cryptographically strong pseudo-random bytes into
.Fa buf .
.Pp
.Fn RAND_pseudo_bytes
puts
.Fa num
pseudo-random bytes into
.Fa buf .
Pseudo-random byte sequences generated by
.Fn RAND_pseudo_bytes
will be unique if they are of sufficient length, but are not necessarily
unpredictable.
They can be used for non-cryptographic purposes and for certain purposes
in cryptographic protocols, but usually not for key generation etc.
.Sh RETURN VALUES
.Fn RAND_bytes
returns 1.
.Fn RAND_pseudo_bytes
returns 1.
.Sh HISTORY
.Fn RAND_bytes
first appeared in SSLeay 0.5.1 and has been available since
.Ox 2.4 .
It has a return value since OpenSSL 0.9.5 and
.Ox 2.7 .
.Pp
.Fn RAND_pseudo_bytes
first appeared in OpenSSL 0.9.5 and has been available since
.Ox 2.7 .
